I'm having a difficult time with the following sumproduct calculation.

The main problem is that I want to sum all cells in column S, that do
not have a value present in the corresponding row in column I. Column
I is sparely populated with some values, the majority of column I has
empty cells. But it's very important that I only calculate column S
where no value is present in column I.

Column D contains names that match cell Y34, column K and N are start
and end dates.

=IF($I$2:$I$4139<"",0,SUMPRODUCT(--($D$2:$D$4139=Y34)*($S$2:$S
$4139),--($K$2:$K$4139=$Y$6),--($N$2:$N$4139<=$Y$7)))

Any help would be greatly appreciated.

Thanks
burl_rfc